Transportation: Major Source of Polluted Runoff

Highways and roads are a major source of stormwater runoff, which is a leading cause of water pollution in the U.S. Roads and related infrastructure, such as parking lots, comprise two-thirds of all paved surfaces, the primary source of stormwater runoff.

American Rivers advocates that roads funded with federal money should better prevent pollution. When the transportation bill is reauthorized, all new and repaired highways should be required to meet a performance based standard that maintains the natural way water would flow over the land, without development. This is achieved by designing roads and using technologies to better absorb and evaporate water, allowing it to be reused instead of polluting local streams and rivers.

Already there are examples of “green street” design successes from around the country.

Roads collect pollutants from tailpipe emissions and brake linings along with other contaminants that wash into rivers and streams during storms, polluting drinking water supplies and taxing downstream communities (see the chart below for the amount of pollution and increased runoff from federal aid roads by state). The increased runoff from these hard surfaces also increases the possibility of flooding and sewer overflows that threaten the safety and health of our communities. Smart stormwater mitigation strategies, such as green roads and highways, are a cost effective way to reduce stormwater pollution, flooding, and help meet clean water requirements.